Spindleless spinning machines have been known for a relatively long time, but to date the problem of reducing the time necessary for threads carrying, yarn breakage elimination, starting the machine and its separate spinning stations continues to call for solution. It is known that modern spindleless spinning machines have a significant number of spinning stations (200 and more), so the productivity of a machine as a whole depends upon the time necessary for performing the yarn carrying and other auxiliary operations which are to be carried out when starting the machine. It must be for this reason that great attention has been paid to the problem of reducing the time necessary for carrying out auxiliary operations by their partial mechanization and automation when new machines are designed and the old ones are improved.
It should be noted that many auxiliary operations necessary to be carried out when repairing yarn breakage are mechanized in modern spindleless spinning machines. Known in the art is, for instance, a spindleless spinning machine (see the FRG Pat. No. 1,560,313, published on Mar. 4, 1973), which has a framework with spinning stations disposed thereon, each of which has a fibres feed unit and a spinning chamber positioned on the framework and having a forming and twisting rotor with a clamp. In addition, a machine comprises a yarn withdrawal unit which has the form of a pair of rollers, and yarn winding devices. A yarn strain indicator, which is electrically connected with the drive of the fibres feed unit, is in contact with the yarn. When the yarn breakage occurs the indicator sends a control signal and the drive of the fibres feed unit stops. At this very moment the forming and twisting rotor and the drive disengage and a respective yarn winding device stops. To restart the spinning process the yarn is fed from the winding device to the forming and twisting rotor which is brought to rotation. Then the drive of the fibres feed unit is started and the yarn twisting-in is carried out. When the process of twisting-in is over the yarn being withdrawn is directed between a pair of rollers of the yarn withdrawal unit and the spinning process continues.
The obvious advantage of the machine under consideration is the fact that the devices which the machine comprises allow comparatively quick elimination of yarn breakage. However, a timely yarn withdrawal on the completion of the twisting-in process continuous to be a problem, and this causes violation of thickness and uniformity of the structure at a certain length.
Known in the art is also a spindleless spinning machine whose construction was improved to overcome this disadvantage (see Specification to accepted application of FRG Pat. No. 2,429,645, published on Jan. 2, 1976). Said machine has a framework whereon a rotation drive and spinning stations are disposed. Each spinning station comprises a fibres feed unit and a spinning chamber having a housing positioned on the framework. Said housing can be withdrawn from the fibres feed unit. In addition, the machine comprises a yarn withdrawal unit whose driving shaft is installed on the framework, and pressing rollers which, when in operating position, are resiliently pressed to said driving shaft and are mounted in such a way that they can be withdrawn from said driving shaft. Besides the aforementioned units, the machine is provided with yarn winding devices each of which is installed near a respective spinning station and comprises a bobbin carrier and a yarn spreader.
A specific peculiarity of the machine is the fact that the pressing rollers are mounted on turnable levers which are pivotally connected to the framework. When the pivoted levers are in operating position, the pressing rollers are engaged with the driving shaft. If the yarn breakes at some spinning station a respective pivoted lever is turned to a position which allows a pressing roller, mounted thereon, and the driving shaft to disengage. The machine has a yarn strain indicator which sends a control signal to the drive of a brake and of the fibres feed unit.
To engage the pressing roller with the driving shaft a respective lever is manually shifted to the operating position. This allows a timely withdrawal of a yarn on the completion of the twisting-in process and thus preventing violation of thickness and uniformity of the yarn structure. Each bobbin carrier has the form of a pivotal lever and allows manual withdrawal of a package from the yarn spreader when repairing the yarn breakage and then returning it thereto when starting.
Thus the following auxiliary operations are to be performed if it is necessary to repair the yarn breakage and then to start a spinning station: withdrawing the housing of the spinning chamber from the fibres feed unit, withdrawing a package from the yarn spreader, withdrawing the pressing roller from the driving shaft, and returning said elements to the initial position after the yarn twisting-in is over. It is quite obvious that the time necessary to perform these operations limits the productivity of the machine as a whole. It should also be noted that the unproductive time necessary to perform these auxiliary operations in a spinning shop equipped with such machines determines to a great extent the number of the attending personnel. In addition, when the spinning station is being started the synchronism of advancing the yarn withdrawal unit and the package to the yarn spreader is sometimes violated with the result that coils may be formed when the yarn spreader having the form of a conoid drum is used, or the yarn may be broken when a yarn spreader having the form of a traverse is used.